介绍了一种由两个相同直角棱镜构成的气室。利用其对光束摆动的不敏感性及对光束的反射特性,来提高气室工作的稳定性和检测灵敏度;分析了传感器中光束的传输特性,给出了光束的传输方程、单波长和双波长情况下光度传感器的测量方程;光束在气室内往返的次数N与过两个直角棱镜各自直角棱的对称面的间距d有关,通过调节间距d可选择所需测量灵敏度。测试结果表明,在低浓度测量时,这种光度传感器的灵敏度为普通单程吸收池灵敏度的N倍;在较高浓度时,仅在N为较小的几个值时,传感器的灵敏度与光束在气室内往返的次数N成正比,N较大时,光束在气室内往返的次数对传感器灵敏度的倍增作用减弱。基于直角棱镜的光纤光度传感器特别适合痕量物质的光度测量。

An air chamber is introduced which is made of two rectangular prisms. Stability and sensitivity of the chamber are improved using the reflectivity character and senseless to tilting of light beam. Transmission characteristics of light beam are analyzed. Transmission equation of probing light beam and measurement equation of the system at both single-wavelength and dual-wavelength are put forward. The times N of light beam going back and forth in the chamber is determined by distance of between planes of symmetry through respective apexes of the prisms. The sensitivity may be chosen by means of adjusting the distance. The results of experiment indicate that the sensitivity of the photometric sensor is N times that of single-pass cell at lower concentration of material to be measured, and when concentration of material is higher, the sensitivity is proportional to the times of light beam going back and forth at the smaller N, and that the times of light beam going back and forth multiplying action on the sensitivity gets weaker at the greater N. The photometric sensor based on rectangular prism with optical fiber is suitable to measuring trace material.